Integrated EGR valve and cooler

ABSTRACT

An exhaust gas recirculation (EGR) cooling system includes a valve and a cooler. A motor opens the valve allowing hot fluid exhaust gas to flow into the valve. Cooling fluid continuously flows in and circulated around the valve, reducing the amount of heat transfer from the hot fluid to the valve components. The hot fluid travels through a plurality of tubes in the cooler, continuing to transfer heat to the cooling fluid. As the hot fluid is cooled, the unburned gas in the hot fluid is recycled to be burned by the engine.

This application claim the benefit of Provisional application Ser. No.60/170,649, filed Dec. 14, 1999.

BACKGROUND OF THE INVENTION

The subject invention relates to exhaust gas recirculation (EGR) withina combustion engine.

EGR systems are increasingly being utilized to improve the efficiency ofengines and reduce the harmful effects of exhaust gas on theenvironment. As an engine burns fuel, it produces an exhaust gas whichcontains unburned fuel and other impurities. The exhaust gas isredirected through the engine to burn any unburned fuel. Reburning theexhaust gas before it is released reduces the harmful effects of theexhaust gas on the atmosphere and enables the vehicle to meet governmentemission standards.

In order to recirculate the exhaust gas, EGR systems typically include avalve and a cooler. The valve regulates the amount of exhaust gas thatis introduced back into the engine. The cooler cools the exhaust gas toa specified temperature which condenses the unburned fuel.

Prior EGR system include a separate valve and cooler. A drawback toutilizing a valve and cooler as separate components is that additionaltubing is necessary, reducing the amount of space in the enginecompartment. Additionally, the additional tubing allows the hot fluid tolose and/or gain heat as it is transported so that there is less controlof the exhaust emission.

SUMMARY OF THE INVENTION

An exhaust gas recirculation (EGR) cooling system includes a valve and acooler. Exhaust gas from the engine is cooled and unburned gas isrecycled back to the engine. Hot fluid exhaust gas from the engineenters the system on a hot side and is returned to the engine on a coldside. The cooler is divided into a shell section for a cooling fluid anda plurality of tubes for the hot fluid. The cooling fluid enters thecooler from the valve and exits the shell through an outlet nozzle. Inthe preferred embodiment, the tubes are such as are available under thetrademark flexfin™.

The valve is attached to the hot side of the cooler and is connected toa motor which controls the opening and the closing of the valve. Thevalve includes a cooling fluid inlet and a hot fluid inlet and has afirst chamber and a second chamber.

The cooling fluid continuously flows in through the cooling fluid inletand into the first chamber. The motor opens the valve to allow the hotfluid to flow into the valve. The subject invention allows the coolingfluid to circulate around the valve in the first chamber, reducing theamount of heat transfer from the hot fluid to the valve components,prolonging the life of the valve. The cooling fluid flows into thesecond chamber and continues to remove heat from the hot fluid beforeentering the cooler. The hot fluid continues to transfer heat to thecooling fluid in the shell as the hot fluid flows through the tubes andexits the tubes at the cold side A. As the hot fluid is cooled, theunburned gas in the hot fluid is recycled to be burned by the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will be readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanying drawingswherein:

FIG. 1 is a schematic of the exhaust gas recirculation system; and

FIG. 2 is a side view of the EGR valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the Figures, wherein like numerals indicate like orcorresponding parts throughout the several views, an exhaust gasrecirculation (EGR) cooling system 10 is shown in FIG. 1. The system 10cools the exhaust gas from an engine and recycles the unburned gas backto the engine. The system 10 has a hot side B where a hot fluid, i.e.the exhaust gas from the engine, enters the system and a cold side Awhere the hot fluid has condensed and is returned to the engine. The EGRsystem 10 comprises a cooler 12 and a valve 14. To those skilled in theart, the cooler 12 acts as a shell and tube heat exchanger. The cooler12 is divided into a shell section 18 for a cooling fluid and aplurality of tubes 20 for the hot fluid. The cooling fluid enters thecooler 12 from the valve 14 and exits the shell 18 through an outletnozzle 24. In the preferred embodiment, the tubes 20 are such as areavailable under the trademark flexfin™, which have a plurality ofspirals for tube walls to increase heat transfer between the hot fluidand the cooling fluid.

The valve 14 is attached to the hot side B of the cooler 12 and has anozzle 40 which is connected to an electric or pneumatic motor. Themotor controls the opening and closing of the valve 14. As seen in FIG.2, the valve components includes a stem 26, an upper housing 27, adiaphragm 28, a diaphragm plate 29, and a spring 30. The valve 14 has acooling fluid inlet 32 and a hot fluid inlet 34. The valve 14 also has afirst chamber 36 and a second chamber 38.

The valve 14 is connected by any known means to the cooler 12. Thecooling fluid continuously flows in through the cooling fluid inlet 32of the valve 14 and into the first chamber 36. When the motor opens thevalve 14, the hot fluid flows into the valve 14. In the prior art, thehot fluid heats up the valve components which shortens the life of thevalve 14. The subject invention allows the cooling fluid to circulatearound the valve stem 26, the diaphragm 28, the diaphragm plate 29, andthe spring 30 in the first chamber 36. The cooling fluid reduces theamount of heat transfer from the hot fluid to the valve components whichin turn prolongs the life of the valve 14. Next, the cooling fluid flowsinto the second chamber 38 of the valve 14 and continues to remove heatfrom the hot fluid before it enters the cooler 12. As the hot fluidflows through the tubes 20, the hot fluid continues to transfer heat tothe cooling fluid in the shell 18. The hot fluid exits the tubes 20 atthe cold side A. As the hot fluid is cooled, the unburned gas in the hotfluid is recycled to be burned by the engine.

There are many additional advantages to connecting and positioning thevalve 14 before the cooler 12. First, the valve 14 remains free ofcontaminants from the cooling of the hot fluid which happens when thevalve 14 is placed after the cooler 12. The second benefit is the hotfluid achieves a more consistent amount of cooling which makes theengine more efficient. If the valve 14 were spaced separately from thecooler, the additional tubing would allow the hot fluid to lose and gainheat as it was transported. Third, by attaching the valve 14 to thecooler 12, the engine achieves better control of the exhaust emissionsbecause the hot fluid temperature out of the cooler is bettercontrolled.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology which has been used is intended to bein the nature of words of description rather than of limitation. It isnow apparent to those skilled in the art that many modifications andvariations of the present invention are possible in light of the aboveteachings. It is, therefore, to be understood that the invention may bepracticed otherwise than as specifically described.

What is claimed is:
 1. An exhaust gas recirculation system comprising: avalve to control a flow of an exhaust fluid entering said system; atleast one tube in fluid communication with said valve, said at least onetube carrying said exhaust fluid from said valve and out of said system;a valve chamber surrounding a portion of said valve, said valveincluding a cooling fluid inlet; and a shell portion defining a coolerchamber in fluid communication with said valve chamber and surroundingsaid at least one tube.
 2. The system as recited in claim 1 wherein anactuator controls a degree of opening of said valve.
 3. The system asrecited in claim 1 wherein said valve includes a stem having a first endand an opposing second end, and said first end of said stem is attachedto and actuated by a diaphragm; a spring attached to said diaphragm andsurrounding a portion of said stem, and a poppet attached to saidopposing second end of said valve.
 4. The system as recited in claim 3wherein said stem, said diaphragm, and said spring are in said valvechamber.
 5. The system as recited in claim 1 wherein said cooling fluidflows through said valve chamber to reduce heat transfer to said valveand further through said shell portion to remove heat from said exhaustfluid flowing through said at least one tube.
 6. The system as recitedin claim 1 wherein said valve further includes a exhaust fluid inlet. 7.The system as recited in claim 1 wherein each of said at least one tubeis helical.
 8. An exhaust gas recirculation system comprising: a valveto control a flow of an exhaust fluid entering said system through a hotfluid inlet; an actuator to control a degree of opening of said valve;at least one tube in fluid communication with said valve said exhaustfluid from said valve and out of said system; a valve chambersurrounding a portion of said valve, said valve including a coolingfluid inlet; and a shell portion defining a cooler chamber in fluidcommunication with said valve chamber and surrounding said at least onetube, said shell portion including a cooling fluid outlet.
 9. The systemas recited in claim 8 wherein said valve includes a stem having a firstend and an opposing second end, and said first end of said stem isattached to and actuated by a diaphragm; a spring attached to saiddiaphragm and surrounding a portion of said stem, and a poppet attachedto said opposing end of said valve.
 10. The system as recited in claim 8wherein each of said at least one tube is helical.
 11. The system asrecited in claim 8 wherein said valve includes a stem having a first endand an opposing second end, and said first end of said stem is attachedto and actuated by a diaphragm, a spring attached to said diaphragm andsurrounding a portion of said stem, and a poppet attached to saidopposing second end of said valve, and wherein said stem, saiddiaphragm, and said spring are in said valve chamber.
 12. An exhaust gasrecirculation system comprising: a valve to control a flow of an exhaustfluid entering said system; at least one tube in fluid communicationwith said valve, said at least one tube carrying said exhaust fluid fromsaid valve and out of said system; a valve chamber including a coolingfluid inlet to allow entry of a cooling fluid into said system, and saidvalve chamber further includes a first chamber and a second chamber forheat removal from said exhaust fluid prior to entry into said shellportion; a shell portion defining a cooler chamber in fluidcommunication with said valve chamber and surrounding said at least onetube to remove hat from said exhaust fluid, said shell portion includinga cooling fluid outlet to convey said cooling fluid from said system.13. An exhaust gas recirculation system comprising: a valve to control aflow of an exhaust fluid entering said system through a hot exhaustinlet; an actuator to control a degree of opening of said valve tocontrol a flow of said exhaust fluid into said valve and said system; atleast one tube in fluid communication with said valve, said at least onetube carrying said exhaust fluid from said valve and out of said system;and a valve chamber surrounding a portion of said valve, said valveincluding a cooling fluid inlet to allow entry of a cooling fluid intosaid system, said cooling fluid reducing heat transfer to said valve andsaid valve chamber includes a first chamber and a second chamber forheat removal from said exhaust fluid prior to entry into said shellportion; and a shell portion defining a cooler chamber in fluidcommunication with said valve chamber and surrounding said at least onetube to remove heat from said exhaust fluid, said shell portionincluding a cooling fluid outlet to convey said cooling fluid from saidsystem.
 14. An exhaust gas recirculation system comprising: a valveincluding a hot exhaust inlet, a stem having a first end and an opposingsecond end, and said first end of said stem is attached to and actuatedby a diaphragm; a spring attached to said diaphragm and surrounding aportion of said stem, and a poppet attached to said opposing end of saidstem; an actuator to control a degree of opening of said valve; at leastone tube in fluid communication with said valve, said at least one tubecarrying said exhaust fluid from said valve and out of said system; anda valve chamber including a first chamber, a second chamber, and acooling fluid inlet said valve chamber surrounding a portion of saidvalve, and a shell portion defining a cooler chamber in fluidcommunication with said valve chamber and surrounding said at least onetube said shell portion including a cooling fluid outlet.
 15. A methodfor cooling an exhaust fluid comprising the steps of: opening a valve tocontrol a flow of said exhaust fluid into an exhaust gas recirculationsystem; removing heat from said valve by flowing said cooling fluid intoa valve chamber surrounding said valve; and removing heat from saidexhaust fluid by further passing said cooling fluid through a shellportion of a cooler in fluid communication with said valve chamber, andsaid shell portion enclosing a plurality of tubes in fluid communicationwith said valve and through which said exhaust fluid flows.
 16. Themethod as recited in claim 15 wherein each of said at least one tube ishelical.